Description
The Timing Error Group (TEG) is a concept introduced in 3GPP Release 17, primarily within positioning and radio resource management specifications (e.g., TS 37.355, 38.331, 38.305). It refers to a set of UEs that are identified by the network—specifically by the Location Management Function (LMF) or the gNB—as exhibiting correlated or similar timing errors. These errors arise from factors like common clock drift, shared propagation environment characteristics (e.g., being in the same indoor area with similar multipath), or being served by the same synchronization source with a known offset. The TEG is not a physical entity but a logical association maintained in the network to optimize positioning procedures and resource allocation for timing-dependent services.
Architecturally, the TEG concept involves several network functions. The LMF, as the central positioning controller, can define TEGs based on positioning measurement reports (e.g., Reference Signal Time Difference (RSTD) measurements for OTDOA) or assistance data requests from UEs. The gNB may also be involved in TEG management for radio resource control, especially for sidelink positioning where UEs directly measure each other. Key components include the positioning protocols (LPP, NRPPa) that can carry TEG identifiers and related error information, the UE capabilities that indicate support for TEG-based procedures, and the network algorithms that cluster UEs into groups based on statistical analysis of their timing measurements.
How it works: The network first identifies UEs suitable for grouping, often during periodic positioning sessions or initial access. For example, multiple sensors in a factory might report timing measurements with a consistent bias due to a shared non-ideal clock source. The LMF assigns these UEs to a TEG and assigns a TEG ID. Subsequently, instead of handling each UE's timing error independently, the network can apply group-level corrections. In positioning calculations, the LMF can compensate for the common error within a TEG, improving the absolute accuracy for all members. For sidelink positioning, UEs in the same TEG can be configured with specific resources or given adjusted timing expectations to improve relative positioning accuracy between them. This group-based approach reduces signaling overhead and computational load compared to per-UE error handling.
Purpose & Motivation
The TEG was created in Release 17 to address the challenges of providing high-accuracy positioning and timing synchronization for new 5G use cases, particularly industrial IoT, vehicle-to-everything (V2X), and enhanced sidelink services. Previous releases handled timing errors on a per-UE basis, which became inefficient and less accurate in scenarios where multiple devices experience similar timing impairments due to shared environmental factors or hardware limitations. For dense deployments like factory sensors or vehicle platoons, individual error estimation and compensation led to excessive signaling and suboptimal positioning performance.
The motivation for TEGs stems from the need for scalable and precise positioning mechanisms in 5G-Advanced. By grouping UEs with correlated errors, the network can achieve several benefits: it reduces the volume of assistance data and measurement reports needed, since common error components can be communicated once for the group; it improves positioning accuracy by enabling network-side compensation of group biases; and it facilitates advanced features like collaborative positioning where UEs within a group help calibrate each other. TEGs specifically solve problems in sidelink-based positioning (e.g., for V2X), where relative timing between UEs is critical, and in scenarios with limited GNSS availability, where UEs must rely on cellular timing that may have group-wise inaccuracies. This concept supports the evolution towards more autonomous and efficient positioning architectures required for mission-critical and commercial applications.
Classification
Detected Changes Across Releases
from 3GPP Change RequestsSpecific changes extracted from the „Change history“ tables of 3GPP specifications (54 CRs across 5 releases). Complements the general historical overview above with the evidence-based evolution of this function.
In Release 15, the TEG (Timing Error Group) function was newly introduced, defining TRP Tx TEG (Tx Timing Error Group) for DL-PRS Resources and detailing the associated Tx Timing Error resulting from uncalibrated or residual Tx Time Delay. This provides a framework for grouping transmission timing errors within a certain margin to aid in positioning accuracy. The related procedures for error handling, such as the transmission of an LPP Error message to abort procedures upon errors, were also specified.
- CR to 38.305 on use of positioning measurement gaps for subframe and slot timing detection towards E-UTRA TS 38.305CR0008
- Correction to Default MAC Cell Group configuration TS 38.331CR0445
- Correction on SI message acquisition timing TS 38.331CR0680
- CR on use of positioning measurement gaps for subframe and slot timing detection towards E-UTRA TS 38.331CR0868
- Clarification of timing reference for CSI-RS resources TS 38.331CR1111
- Modified UE capability on different numerologies within the same PUCCH group TS 38.331CR1115
+ 3 more changes
In Release 16, the Timing Error Group (TEG) function was introduced to characterize and group timing errors for positioning accuracy. Specifically, it defined Tx Timing Error as the uncalibrated or residual delay from baseband signal generation to RF transmission, and Rx Timing Error as the delay from RF reception to baseband digitization. These definitions allowed for the calibration and grouping of errors from multiple DL-PRS resources within a specified margin to improve location estimation.
- Aperiodic CSI-RS triggering with beam switching timing of 224 and 336 TS 38.331CR1716
- Implementing confirmation of code block group based transmission TS 38.331CR1717
- Introduction of secondary DRX group CR 38.331 TS 38.331CR1632
- NR-DC Cell Group capability filtering TS 38.331CR2703
- NAS handling error of nas-Container for security key derivation TS 38.331CR1149
- Correction on HARQ ACK spatial bundling configurations for secondary PUCCH group TS 38.331CR1993
+ 4 more changes
In Release 17, the TEG function was enhanced by introducing explicit support for timing error margins for TEGs in the NRPPa and F1AP interfaces, while removing the UE Tx TEG Association from F1AP. Corrections were made to the applicability of the timing error margin for RxTEG in measurement reporting fields and to the configuration and capability signaling for both UE and TRP TEGs. These changes refined the procedures for transferring capabilities and reporting errors related to timing error groups within the LPP positioning framework.
- Addition of Timing Advance measurement reporting in NR E-CID [NRTADV] TS 38.305CR0082
- Addition of NR Timing Advance reporting for NR UL E-CID [NRTADV] TS 38.455CR0042
- Addition of NR Timing Advance reporting for NR UL E-CID [NRTADV] TS 38.473CR0817
- Adding UE capability of CSI reporting cross PUCCH SCell group TS 38.331CR3144
- Corrections on applicability of timing error margin of RxTEG in NR-Multi-RTT-SignalMeasurementInformation field descriptions and other Miscellaneous corrections TS 37.355CR0431
- Correction to UE TEG Capability TS 37.355CR0475
+ 15 more changes
In Release 18, the TEG (Timing Error Group) function was enhanced with a specific correction to the UL TEG report procedure. This release also introduced broader 5G Timing Resiliency and URLLC enhancements, which encompass the TEG framework for managing Tx and Rx Timing Errors associated with DL-PRS and UL SRS signals. These updates were accompanied by corrections to the timing reporting granularity factor and the timing synchronisation status reporting procedure.
- Introduction of URLLC and Timing Resiliency TS 38.331CR4258
- Corrections and Updates to UE capabilities for RAN1 feature group 55-6 TS 38.331CR4862
- Introduction of 5G Timing Resiliency and URLLC enhancements TS 38.473CR1168
- Correction for timing Reporting Granularity Factor TS 37.355CR0560
- Corrections to URLLC and Timing Resiliency TS 38.331CR4624
- Corrections to URLLC and Timing Resiliency TS 38.331CR4667
+ 7 more changes
In Release 19, the new feature for the Timing Error Group (TEG) function is not described in the provided grounding context. The context defines fundamental terms like TRP Tx TEG, Tx Timing Error, and Rx Timing Error but contains no information on Release 19-specific enhancements. The listed Change Request title pertains to beam reporting and is unrelated to TEG functionality.
- Correction on dependency of group-based beam reporting TS 38.331CR5544
Explore further
Broader topics and technologies where TEG plays a role.
Defining Specifications
3GPP specifications that define or reference TEG, with the latest known release. Sourced from the 3GPP document catalog — see methodology.
| Specification | Title | Release |
|---|---|---|
| TS 37.355 vj20 | LTE Positioning Protocol (LPP) | Rel-19 |
| TS 37.571 vj00 | UE Conformance for Positioning | Rel-19 |
| TS 38.305 vj00 | NG-RAN UE Positioning Stage 2 | Rel-19 |
| TS 38.331 vj00 | NR Radio Resource Control (RRC) Protocol Specification | Rel-19 |
| TS 38.455 vj10 | NR Positioning Protocol A (NRPPa) | Rel-19 |
| TS 38.473 vj10 | 5G F1 Application Protocol (F1AP) | Rel-19 |